Enhancing combustion performance of nano-Al/PVDF composites with β-PVDF

TY - JOUR

T1 - Enhancing combustion performance of nano-Al/PVDF composites with β-PVDF

AU - Huang, Sidi

AU - Hong, Sungwook

AU - Su, Yingchun

AU - Jiang, Yue

AU - Fukushima, Shogo

AU - Gill, Thomas Mark

AU - Yilmaz, Nil

AU - Tiwari, Subudh

AU - Nomura, Ken-ichi

AU - Kalia, Rajiv

AU - Nakano, Aiichiro

AU - Shimojo, Fujuki

AU - Vashishta, Priya

AU - Chen, Menglin

AU - Zheng, Xiaolin

PY - 2020

Y1 - 2020

N2 - Solid energetic nanocomposites, consisting of reactive metal particles and oxidizers, find broad applications ranging from pyrotechnics to solid rocket propellants and solid ramjet fuels. In particular, nano-aluminum (n-Al) and polyvinylidene fluoride (PVDF) are attractive fuel and oxidizer materials, due to the high energy density of n-Al, and the high oxidizing potential and excellent mechanical properties of PVDF. PVDF is a semi-crystalline polymer and has three common crystalline phases, alpha (α), gamma (γ), and beta (β) phases. Many research works have focused on the chemical reactions between Al and PVDF, yet the effect of PVDF crystallinity on the Al/PVDF reaction is unknown. Here, we experimentally and computationally demonstrate that increasing the mass fraction of β-phase PVDF from 2.5 to 25% in Al/PVDF composites substantially improves peak pressure by 90% (from ~34 to ~64 psi) and pressure rise rates by 300% (from 2.5 psi/ms to 10 psi/ms). This stems from the alignment of F atoms along one side of the β-PVDF polymer chain, making it structurally conducive to reacting with Al particles to form strong Al-F interactions. This strong interaction leads to higher binding energy between, and hence higher reactivity in, β-PVDF and Al. Our research provides a new method for enhancing the reactive performance of Al/PVDF composites by increasing the content of β-PVDF.

AB - Solid energetic nanocomposites, consisting of reactive metal particles and oxidizers, find broad applications ranging from pyrotechnics to solid rocket propellants and solid ramjet fuels. In particular, nano-aluminum (n-Al) and polyvinylidene fluoride (PVDF) are attractive fuel and oxidizer materials, due to the high energy density of n-Al, and the high oxidizing potential and excellent mechanical properties of PVDF. PVDF is a semi-crystalline polymer and has three common crystalline phases, alpha (α), gamma (γ), and beta (β) phases. Many research works have focused on the chemical reactions between Al and PVDF, yet the effect of PVDF crystallinity on the Al/PVDF reaction is unknown. Here, we experimentally and computationally demonstrate that increasing the mass fraction of β-phase PVDF from 2.5 to 25% in Al/PVDF composites substantially improves peak pressure by 90% (from ~34 to ~64 psi) and pressure rise rates by 300% (from 2.5 psi/ms to 10 psi/ms). This stems from the alignment of F atoms along one side of the β-PVDF polymer chain, making it structurally conducive to reacting with Al particles to form strong Al-F interactions. This strong interaction leads to higher binding energy between, and hence higher reactivity in, β-PVDF and Al. Our research provides a new method for enhancing the reactive performance of Al/PVDF composites by increasing the content of β-PVDF.

KW - Beta phase PVDF

KW - Combustion

KW - Energetic materials

KW - Nano-aluminum

KW - Nanocomposites

KW - PVDF

UR - http://www.scopus.com/inward/record.url?scp=85086920700&partnerID=8YFLogxK

U2 - 10.1016/j.combustflame.2020.06.011

DO - 10.1016/j.combustflame.2020.06.011

M3 - Journal article

SN - 0010-2180

VL - 219

SP - 467

EP - 477

JO - Combustion and Flame

JF - Combustion and Flame

ER -